Vehicles having combustion engines can employ filters for collecting particulate emitted from the engines. Engine particulate collected by a filter causes the exhaust back pressure to increase, adversely affecting fuel economy and vehicle performance. A regeneration method is required for successful operation of the engine particulate filters.
One way to regenerate a particulate filter is to oxidize the collected particulate. A problem with this approach is that the oxidation temperature of the collected particulate (carbon) lies above the temperature range of the exhaust of most vehicles having combustion engines. Some form of external energy is used to increase the filter temperature such that the oxidation temperature is reached and the filter can regenerate. Electrical heaters and fuel burners are two such external energy systems, but are not viable for vehicles due to increased cost, complexity, and reliability.
Another way to regenerate a particulate filter is to use a catalyst to lower the oxidation temperature of the collected particulate. Catalysts can either be applied as a filter coating or as an additive added to the fuel of the vehicle. The advantage of fuel additives to promote regeneration is that the catalyst is contained within the particulate trapped by the filter. A fuel additive dosing system adds the additive to the fuel.
The fuel additive dosing system must add a determined amount of the additive to the fuel to maintain a desired fuel/additive ratio. Typical fuel additive dosing systems use the fuel level sender gauge located in the fuel tank to monitor the fuel level in the fuel tank. The typical fuel additive dosing systems gain information about the refueling operations such as the amount of fuel added during refueling by using the fuel level gauge.
A problem with using the fuel level gauge in the fuel tank is that the reading from the fuel level gauge is typically not accurate enough for fuel additive dosing systems. Fuel level gauges are also prone to having erroneous fuel readings when the fuel tank is full or nearly empty.
Because the fuel level reading regarding the amount of fuel in the fuel tank is not typically accurate, the fuel additive dosing systems add an improper amount of the additive to the fuel. The improper amount may be more or less than the amount required for maintaining the desired fuel/additive mixture ratio. This causes the actual fuel/additive ratio to be different than the desired fuel/additive ratio. Deviance from the desired fuel/additive ratio must be kept to a minimum for proper filter performance.
What is needed is a more accurate way of determining the amount of fuel in a vehicle or added to a vehicle for fuel additive dosing methods and systems.